Luminescence enhancement of Y2O3:Er3+ and Y2O3:Yb3+/Er3+ sub-microcrystals by Zr4+ ions Co-doping

The co-doping effect of Zr 4+ ions on upconversion (UC) luminescent properties in visible region of Y 2 O 3 : Er 3+ and Y 2 O 3 : Er 3+ , Yb 3+ sub-microcrystals prepared by urea precipitation method has been investigated under 980 nm excitation. Compared with the original Y 2 O 3 : Er 3+ and Y 2 O 3 : Er 3+ , Yb 3+ sub-microcrystals, the UC luminescence of sub-microcrystals with similar size was enhanced after Zr 4+ ions co-doping. The UC luminescent properties have been discussed in detail via luminescence spectra, decay curve analysis and a suitable energy level diagram. The enhancement mechanism of UC luminescence in the two series of Zr 4+ ions doped sub-microcrystals was attributed to the complex crystal field around Er 3+ ions caused by Zr 4+ ions co-doping. After Zr 4+ ions substituted Y 3+ ions and entered the crystal lattice, the charge mismatch and lattice distortion made the crystal field more complex. This research contributes to the understanding of UC luminescent properties of lanthanide (Ln 3+ ) ions doped UC materials and their technological applications in fields such as bioimaging, drug delivery, and optical temperature sensors.